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Viruses. Virus: Particles of nucleic acid, protein, some lipids Reproduce vicariously Use the cells they infect to build new viruses.

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Presentation on theme: "Viruses. Virus: Particles of nucleic acid, protein, some lipids Reproduce vicariously Use the cells they infect to build new viruses."— Presentation transcript:

1 Viruses

2 Virus: Particles of nucleic acid, protein, some lipids Reproduce vicariously Use the cells they infect to build new viruses

3 Viruses: Nucleic Acids: -DNA or RNA -single strand or double strand Capsid: proteins coat that enables infection of cell

4 Viral Specificity and Adaptation -Infections are highly specific (animal viruses, bacterial viruses, etc.) -Viruses evolve to “jump” species lines -Evolution occurs when the virus takes up DNA from host

5 Virus Forms

6 Pathogenicity and Virulence Pathogenicity: The ability of a microbe to cause disease Virulence: degree of pathogenicity -measured by infection rates or fatality

7 2 forms of Infection 1.Lytic: bursts host cell 2.Lysogenic: doesn’t burst cell

8 1. Lytic Infection Steps 1.Virus enters host cell 2.Releases DNA/RNA 3.Host transcribes and translates viral nucleic acid 4.Host assembles new viruses 5.New viruses break out of cell and infect new cells

9 2. Lysogenic Cycle 1.Viral DNA is integrated into host cell’s 2.Replicates the virus DNA with its own 3.Virus remains dormant 4.May enter the lytic cycle

10 Retroviruses -Contain RNA -Inserts into the DNA of host -Genetic info is copied backwards -Often used in biotech Ex. Gene therapy for Cystic Fibrosis

11 Gene Therapy


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